if our skin cells are constantly dying and being replaced by new ones, how can a bad sunburn turn into cancer YEARS down the line?
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Well, cells divide or are eaten. When the cell takes in too much sun and divides, it can replicate in a bad way. Make that happen a few more times, and the cell goes from a little bad or off to cancer.
The sun damages cells deeper than our natural shedding occurs. Tattoos go this deep, that’s why they stay, but are still visible because they aren’t too deep. The sun can penetrate deeper than a tattoo and it’s damage to the deeper layers that turn cancerous
All it takes is one damaged cell.
Then that divides and passes on the damage.
Harmless at first because it isnt too broken, but every new copy frays juuuust a little more until one bad split.
That one bad split has that cell go ABSOLUTELY BONKERS possibly even recruiting all of the cells near it with that damage to start joining it, being considered “one of us” by the broken cell.
Since these cells are just trying to split and split and “repair” damage that isnt there, the cells start filling a gap that isnt there.
Normally the body sees broken cells and gets rid of them like any other foriegn material, but these cells break in juuuust such a way that the body still thinks they’re ok and, so, ignores them.
So, that tiny mole from sun exposure could, years down the line, have one of those melanin producing cells break and suddenly you have melanoma. Like making a copy of a copy of a copy on a copy machine, if you spill something on the page, it might not show too poorly on the first copy. But by the 11th copy of a copy that faint grey from the background might become a big garbled mess as more and more data gets corrupted.
Sun damage works because radiation from the sun actually damages the processes in which cells replicate.
Sunburn damages the top layers to where the cells are destroyed completely. But it also causes much more fundamental damage to the cells below the flaky skin, altering them.
Consider a cell, it has RNA which copies DNA allowing it to split into new cells. RNA is extremely precise. It gets the process right 99.999…% of the time, and maybe there is a mutation in there, but often times it’s inconsequential and only adds up over millennia.
RNA works because it itself has an extremely rigid set of instructions on how it does its job. However, if a highly charged particle from the sun comes down, and directly hits a part of it that had key information, damaging it, but not killing it, the RNA cell will just plough on through and continue working as if nothing has changed. Only now it’s producing malformed outputs, which will themselves eventually produce malformed outputs as they inherit the now corrupt information given to them by their parent.
Of course, this works on statistics. Given enough time in the sun, eventually the chance you’ll damage RNA and get something like cancer reaches 100%. Of course, some people are luckier than others when it comes to getting cancer in their lifetimes.
So, when you’re burned by the sun, the burned cells die and flake off, but the cells underneath could now be irrevocably altered. Constantly producing bad new skin cells that manifest themselves as a cancer. Cutting out the damaged skin cells, or otherwise destroying them is the only way to stop it replicating further.
Every time cell divides there is a risk of something going wrong, regularly things do, but the cell and our immune system deal with it by repairing the cell or by eradication. More damage you do, the more dices you roll.
Now the reason we get sunburn is that UV radiation destroys the cells internal working by destroying the dna so the cells machinery can’t read it, or by damaging the system that reads it. Cells don’t have working memory, everything they do, they take the instructions from DNA.
So a slight error in the instructions will lead to accumulation of errors. Correct errors over time this can lead to cancer.
Keep in mind that surface of our skin is dead cells, and under it there are living cells replicating.
This sane mechanism of errors in the cell leading to cancer can be caused by other things, like viruses that don’t kill the cell after or during attack, or chemicals. The key is the accumulation of errors leading to cell dividing in aggressive and uncontrolled manner. From the perspective of the cell, it is behaving correctly.
Each cell is a copy of a copy. Imagine doing a photocopy of a document and each new copy isn’t based on the original, but the latest photocopy.
Eventually it’ll become more and more degraded, and eventually it won’t be readible everywhere.
Bad sunburn is, essentially, damaging one of those copies. Meaning it’s even more likely that the copy of that copy will be slightly worse off.
Cancer is a percentages game – some things increase the probability of a mutation and there’s a chance that mutation could be cancerous.
Sunburn and UV radiation is one of those factors that can damage your cells and their DNA, making it more likely that a copy comes out damagged.
Not the post i want to be at the top of my front page after I just came back from Kayaking with a massive sunburn.
It’s not just “the cell” that gets damaged, but the instruction manual or programming code it uses to know what to do that gets damaged or edited. That edited code gets passed to any copies it makes. If enough of those edits and changes accumulate over time in that lineage of cell, it can become cancerous. The code that tells it to self destruct can be broken, or the part that regulates its growth or rate or reproduction could be edited in ways that makes it take on a life of its own, rather than working in harmony with the rest of your body.
I’m going to split your question into 2 parts:
1) how can skin become cancerous if its cells are constantly dying and being replaced?
2) how can skin cancer develop years after damage?
1: Cancer is made of cells that have failed to die. When cells become damaged, they normally self destruct to protect the other cells. If they don’t, your body steps in to remove them. However, sometimes your body doesn’t notice. In this case, the damaged cells can keep growing unchecked.
2: Not all skin cells are born to die. Skin cells constantly grow from a layer of parent cells, and gradually push each other up towards the surface, where they die. If the parent cell layer becomes damaged, that damage will be passed on to all the skin cells it makes, and any replacement ‘parent cells’ it makes. Over time, more and more damage can build up, until years later, random chance or another sunburn tips them over the edge.
The sunburn damages the cell’s nucleus and mutates the DNA within. The cell now reproduces with incorrect directions, so the result is a tumor (cells that are put together incorrectly). That tumor may or may not be cancerous, if it is then it typically grows and spreads very slowly at first because it started with a small group of cells. The larger the group of cancerous cells become, the faster it divides and the faster it grows/spreads.
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